A machine tool comprising a tool magazine storing tools and a tool changer capable of automatically exchanging a tool is known in general. The spindle of such a machine tool has a structure capable of automatically attaching/detaching a tool so that the tool changer can automatically exchange the tool mounted on the spindle. In order to exchange the tool mounted on the spindle of the machine tool, it is necessary to release the tool from the spindle of the machine tool through the tool changer. Japanese Patent No. 3083921 describes an exemplary tool changer.
This tool changer comprises a support frame, a rotary shaft connected to a motor, a cam formed on this rotary shaft, an upper shaft portion supported by the support frame and pressed by the cam, a drawbar pressed by the upper shaft portion, disc springs upwardly urging the drawbar, support springs pressing the upper shaft portion in a direction for separating from the drawbar and an oil supply mechanism supplying cutting oil.
In the tool changer having this structure, the contact position between the outer peripheral surface of the cam and the upper shaft portion is upwardly displaced upon completion of a tool unclamping operation. The upper shaft portion is displaced in the direction for separating from the drawbar due to pressing force from the support springs. Further, the drawbar is upwardly displaced due to pressing force from the disc springs. A spindle grasps an exchanged tool.
Patent Document 1: Japanese Patent No. 3083921